Abundance of mosquito species within sokoto metropolis

Thesis Overview

<p> 1.0 INTRODUCTION<br>Mosquitoes are slender and relatively small insects, usually measuringabout 3–<br>6 mm in length. Some species, however, can be as small as 2 mmwhile others may<br>be as long as 19 mm (Service, 2008). The long antennae have numerous whorls of<br>hair, short in the female and long and bushy in the male. In most species of<br>mosquitoes, the mouthparts of the female are long, adapted for piercing and for<br>sucking blood. The male, which feeds on nectar and water, has rudimentary<br>mouthparts. Females of this group prefer the blood of warm-blooded animals.<br>When they bite, they inject some of their salivary fluid into the wound, causing<br>swelling and irritation. Many inject infectious microorganisms and thus transmit<br>such diseases as malaria, yellow fever, dengue, and filariasis (Patel et al, 2012).<br>There are some 3300 species of mosquitoes belonging to 41 genera, all<br>contained in the family Culicidae (Service, 2008). This family is divided into three<br>subfamilies: Toxorhynchitinae, Anophelinae (anophelines) and Culicinae<br>(culicines). Mosquitoes have a worldwide distribution; they occur throughout the<br>tropical and temperate regions and extend their range northwards into the Arctic<br>Circle. The only areas from which they are absent are Antarctica, and a few<br>islands. They are found at elevations of 5500mand down mines at depths of 1250m<br>below sea level (Service, 2008).<br>10<br>The most important pest and vector species belong to the genera Anopheles,<br>Culex, Aedes, Ochlerotatus, Psorophora, Haemagogus and<br>Sabethes.Anophelesspecies, as well as transmitting malaria, are vectors of<br>Filariasis (Wuchereriabancrofti, Brugiamalayi and Brugiatimori) and a few<br>arboviruses. Certain Culexspecies transmit Wuchereriabancrofti and a variety of<br>arboviruses. Aedes species are important vectors of yellow fever, dengue,<br>encephalitis viruses and many other arboviruses, and in a few restricted areas they<br>are also vectors of Wuchereriabancrofti and Brugiamalayi. Species in the very<br>closely related genus Ochlerotatus also transmitfilariasis and encephalitis viruses.<br>Mansonia species transmit Brugiamalayi and sometimes<br>Wuchereriabancrofti and a few arboviruses. Haemagogus and Sabethes<br>mosquitoes are vectors of yellow fever and a few other arboviruses in Central and<br>South America, while the genus Psorophora contains some troublesome pest<br>species in North and South America, as well as a few transmitting arboviruses<br>(Service, 2008).<br>Many species, although not carriers of any disease, can nevertheless be<br>troublesome because of the serious biting nuisances they cause.<br>The mosquito is one of the insects that have come to be known by man<br>especially in homes for their bites which elicits the formation of antibodies. This is<br>due to the venom that contains toxic protein, which may be inoculated as a result of<br>11<br>these bites. It can also cause sharp-pains with some allergic tendencies. Although it<br>does not only bite, but can also serve as nuisance by causing discomfort to their<br>hosts (especially higher vertebrates) as a result of their sounds(Richard, 1993).<br>Mosquitoes are also widely spread due to their high adaptability, higher<br>reproductive rate, wings, which makes them long distance travellers. Mosquitoes lay<br>their eggs in places where stagnant waters are found. For example pools, ditches,<br>gutters, rivers, streams and other places (Patel et al., 2012)<br>Although some species of mosquitoes do not bite people, rather they prefer<br>birds or amphibians hosts. Certain mosquito species prefers to feed during the<br>daytime, while others feed at night (Ilahi,2013). Various mosquito species have<br>evolved to seek out and lay their eggs in specific locations (Patriciaet al., 2014).<br>Female mosquitoes lay their eggs only in water; some species lay their eggs<br>in running water, others in woodland pools, marshes, swamps, estuaries, or in<br>containers such as rain barrels (Service, 2008).<br>1.1 STATEMENT OF THE RESEARCH PROBLEM<br>Mosquitoes are vicious biters and their bites constitute biting nuisance,<br>allergic reactions, skin irritations, scratching, restlessness and sleepless nights<br>(Onyidoet al., 2009). Some biteduring the day while others bite during the night or<br>at both night and day periods. Through their blood sucking habits, they act as<br>vectors of a variety of human pathogens including viruses, bacteria, protozoa and<br>12<br>helminthic diseases. They transmit to man such deadly diseases as malaria, yellow<br>fever, filariasis,dengue and various forms of viral encephalitis (Ukpaiand Ajoku,<br>2003).<br>The anopheles mosquitoes especially, Anophelesgambiae, transmit malaria<br>and filariasis. The Aedesmosquitoes particularly Aedesaegypti, A. albopictus, A.<br>africanus, A. luteocephalusand A. simpsoni, transmit yellow fever, dengue,<br>haemorrhagic fevers and various forms of viral encephalitis. The Culexmosquitoes<br>particularly Culex quinquefasciatus are very important transmitters of filarial<br>worms especially Wuchereriabancrofti which causes elephantiasis. They also<br>transmit various forms of viral encephalitis (Onyidoet al., 2009).<br>Mosquitoes also bite livestock and transmit some animal diseases like fowl<br>pox disease of poultry, myxomatosis of rabbits, rift valley fever of sheep,<br>encephalitis of horses and heartworm disease of dogs (Service, 1980).<br>All these diseases cause high death toll on both human and animal<br>populations and lead to poor socio-economic development of many countries.<br>1.2 SIGNIFICANCE OF THE RESEARCH<br>The mosquitoes remain a major vector of killer diseases in every part of the<br>world, and Nigeria is not an exception. They also cause nuisance by the sound they<br>make. But they serve as a vital ecological function in that their larvae, pupae, and<br>13<br>adults are important food source for fishes, birds, bats, frogs and insects (Patricia et<br>al., 2014).<br>Although the occurrence of various species of mosquitoes may be seen to<br>vary from one location to another, the result obtained in this study would high-light<br>some important information on the diversity and distribution of mosquitoes as well<br>as help in designing an effective control measure.<br>1.3 AIM AND OBJECTIVES OF THE RESEARCH<br>The aim of the research is to determine the relative abundance and<br>distribution of mosquito species within Sokoto Metropolis.<br>The objectives of this research are to:<br>ï‚· Identify the species within the areas under study.<br>ï‚· Determine the most abundant species within the area.<br>ï‚· Determine the distribution of mosquito species within the study areas based<br>on area of collection, sex and feeding state. <br></p>